NEW YORK, NY - APRIL 16: A National Guard soldier keeps watch during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it has continued increased security one day after the Boston Marathon bombings. less

NEW YORK, NY - APRIL 16: A National Guard soldier keeps watch during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it has continued increased security ... more

Photo: Mario Tama, Getty Images

NEW YORK, NY - APRIL 16: A National Guard soldier keeps watch... Photo-4479708.60532 - Times Union

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NEW YORK, NY - APRIL 16: A police K-9 unit dog sniffs newspaper boxes for explosives outside of Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the Boston Marathon killed 3 people and wounded more than 170 others. less

NEW YORK, NY - APRIL 16: A police K-9 unit dog sniffs newspaper boxes for explosives outside of Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after ... more

Amtrak police officers and their dogs watch as commuters walk through Penn Station, Tuesday, April 16, 2013 in New York. The deadly explosions at the Boston Marathon on Monday reverberated on both sides of the Atlantic as cities from Los Angeles to London saw a surge in security. less

Amtrak police officers and their dogs watch as commuters walk through Penn Station, Tuesday, April 16, 2013 in New York. The deadly explosions at the Boston Marathon on Monday reverberated on both sides of the ... more

Police officers keep an eye on commuters in a subway station in New York, Tuesday, April 16, 2013. Police armed with rifles and extra patrol cars were stationed around the city Tuesday as New York remained in a heightened state of alert until more is known about the bombings at the Boston Marathon. less

Police officers keep an eye on commuters in a subway station in New York, Tuesday, April 16, 2013. Police armed with rifles and extra patrol cars were stationed around the city Tuesday as New York remained in a ... more

Photo: Seth Wenig, AP

Police officers keep an eye on commuters in a subway station in New... Photo-4479692.60532 - Times Union

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Taboola Gallery Frame Item-85307.60532 - Times Union

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NEW YORK, NY - APRIL 16: A police K-9 unit stands by as train passengers pass through Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the Boston Marathon killed 3 people and wounded more than 170 others. less

NEW YORK, NY - APRIL 16: A police K-9 unit stands by as train passengers pass through Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near ... more

Photo: John Moore, Getty Images

NEW YORK, NY - APRIL 16: A police K-9 unit stands by as train... Photo-4479693.60532 - Times Union

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NEW YORK, NY - APRIL 16: New York Police Department officers inspect bags at a subway entrance during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it has continued increased security one day after the Boston Marathon bombings. less

NEW YORK, NY - APRIL 16: New York Police Department officers inspect bags at a subway entrance during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it ... more

Photo: Mario Tama, Getty Images

NEW YORK, NY - APRIL 16: New York Police Department officers... Photo-4479697.60532 - Times Union

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NEW YORK, NY - APRIL 16: Police check a subway passenger's bag at Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the Boston Marathon killed 3 people and wounded more than 170 others. less

NEW YORK, NY - APRIL 16: Police check a subway passenger's bag at Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of ... more

A Police officer keep an eye on commuters in a subway station in New York, Tuesday, April 16, 2013. Police armed with rifles and extra patrol cars were stationed around the city Tuesday as New York remained in a heightened state of alert until more is known about the bombings at the Boston Marathon. less

A Police officer keep an eye on commuters in a subway station in New York, Tuesday, April 16, 2013. Police armed with rifles and extra patrol cars were stationed around the city Tuesday as New York remained in ... more

Photo: Seth Wenig, AP

A Police officer keep an eye on commuters in a subway station in... Photo-4479700.60532 - Times Union

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Taboola Gallery Frame Item-85307.60532 - Times Union

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NEW YORK, NY - APRIL 16: A police K-9 unit stands by as train passengers pass through Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the Boston Marathon killed 3 people and wounded more than 170 others. less

NEW YORK, NY - APRIL 16: A police K-9 unit stands by as train passengers pass through Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near ... more

Photo: John Moore, Getty Images

NEW YORK, NY - APRIL 16: A police K-9 unit stands by as train... Photo-4479701.60532 - Times Union

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A New York City Police officer watches as people take pictures with the bull statue in the Financial District, Tuesday, April 16, 2013 in New York. Law enforcers say New York City remains in a heightened state of alert until more is known about the Boston explosions. More officers are working around New York, including counterterrorism units and beefed up patrols. less

A New York City Police officer watches as people take pictures with the bull statue in the Financial District, Tuesday, April 16, 2013 in New York. Law enforcers say New York City remains in a heightened state ... more

Photo: Richard Drew, AP

A New York City Police officer watches as people take pictures with... Photo-4479702.60532 - Times Union

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NEW YORK, NY - APRIL 16: An Amtrak police special operations unit stands by outside of Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the Boston Marathon killed 3 people and wounded more than 170 others. less

NEW YORK, NY - APRIL 16: An Amtrak police special operations unit stands by outside of Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near ... more

Photo: John Moore, Getty Images

NEW YORK, NY - APRIL 16: An Amtrak police special operations unit... Photo-4479706.60532 - Times Union

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NEW YORK, NY - APRIL 16: People depart an arriving train during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it has continued increased security one day after the Boston Marathon bombings. less

NEW YORK, NY - APRIL 16: People depart an arriving train during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it has continued increased security one day ... more

Photo: Mario Tama, Getty Images

NEW YORK, NY - APRIL 16: People depart an arriving train during... Photo-4479707.60532 - Times Union

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Taboola Gallery Frame Item-85307.60532 - Times Union

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NEW YORK, NY - APRIL 16: Metropolitan Transit Authority (MTA) police officers keep watch during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it has continued increased security one day after the Boston Marathon bombings. less

NEW YORK, NY - APRIL 16: Metropolitan Transit Authority (MTA) police officers keep watch during the morning commute in Grand Central Terminal on April 16, 2013 in New York City. The city announced it has ... more

NEW YORK, NY - APRIL 16: An Amtrak police special operations unit stands by outside of Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the Boston Marathon killed 3 people and wounded more than 170 others. less

NEW YORK, NY - APRIL 16: An Amtrak police special operations unit stands by outside of Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near ... more

Photo: John Moore, Getty Images

NEW YORK, NY - APRIL 16: An Amtrak police special operations unit... Photo-4479712.60532 - Times Union

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NEW YORK, NY - APRIL 16: Commuter passengers move through Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the Boston Marathon killed 3 people and wounded more than 170 others. less

NEW YORK, NY - APRIL 16: Commuter passengers move through Penn Station on April 16, 2013 in New York City. Police were out in force throughout New York, a day after explosions near the finish line of the ... more

NEW YORK, NY - APRIL 16: The outside of Yankee Stadium supports the victims of the bombings at the Boston Marathon before the game between the Arizona Diamondbacks the New York Yankees on April 16, 2013 at Yankee Stadium in the Bronx borough of New York City. In light of the bombings at the Boston Marathon on Monday, New York City has increased security. less

NEW YORK, NY - APRIL 16: The outside of Yankee Stadium supports the victims of the bombings at the Boston Marathon before the game between the Arizona Diamondbacks the New York Yankees on April 16, 2013 at ... more

Photo: Elsa, Getty Images

NEW YORK, NY - APRIL 16: The outside of Yankee Stadium supports... Photo-4484393.60532 - Times Union

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Taboola Gallery Frame Item-85307.60532 - Times Union

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A police officer uses a mirror to check the undercarriage of a vehicle entering a nearby parking garage before a baseball game between the New York Yankees and Arizona Diamondbacks at Yankee Stadium in New York, Tuesday, April 16, 2013. Signs of increased security were visible around the stadium in the wake of the Boston Marathon explosions. less

A police officer uses a mirror to check the undercarriage of a vehicle entering a nearby parking garage before a baseball game between the New York Yankees and Arizona Diamondbacks at Yankee Stadium in New ... more

Photo: Kathy Willens, AP

A police officer uses a mirror to check the undercarriage of a... Photo-4484398.60532 - Times Union

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Police officers patrol in front of Yankee Stadium before a baseball game between the New York Yankees and Arizona Diamondbacks in New York, Tuesday, April 16, 2013. Signs of increased security were visible in the wake of the Boston Marathon explosions. less

Police officers patrol in front of Yankee Stadium before a baseball game between the New York Yankees and Arizona Diamondbacks in New York, Tuesday, April 16, 2013. Signs of increased security were visible in ... more

Photo: Kathy Willens, AP

Police officers patrol in front of Yankee Stadium before a baseball... Photo-4484401.60532 - Times Union

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Security personnel stand in front of a PATH train station at the World Trade Center site in New York, Tuesday, April 16, 2013. Police armed with rifles and extra patrol cars were stationed around the city Tuesday as New York remained in a heightened state of alert until more is known about the Monday bombings at the Boston Marathon. less

Security personnel stand in front of a PATH train station at the World Trade Center site in New York, Tuesday, April 16, 2013. Police armed with rifles and extra patrol cars were stationed around the city ... more

Photo: Seth Wenig, AP

Security personnel stand in front of a PATH train station at the... Photo-4484410.60532 - Times Union

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HICKSVILLE, NY - APRIL 15: A police officer with his K-9 companion keeps guard as a Long Island Rail Road train from New York City arrives at the station on April 15, 2013 in Hicksville, New York. According to reports, at least two people were killed and 28 injured in two blasts near the finish of the Boston Marathon on Monday. less

HICKSVILLE, NY - APRIL 15: A police officer with his K-9 companion keeps guard as a Long Island Rail Road train from New York City arrives at the station on April 15, 2013 in Hicksville, New York. According to ... more

Photo: Bruce Bennett, Getty Images

HICKSVILLE, NY - APRIL 15: A police officer with his K-9 companion... Photo-4479711.60532 - Times Union

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A police officer patrols the area in front of the Barclays Center in New York, Monday, April 15, 2013, before a Brooklyn Nets NBA basketball game in the wake of the explosions at the Boston Marathon. (AP Photo/Kathy Willens) less

A police officer patrols the area in front of the Barclays Center in New York, Monday, April 15, 2013, before a Brooklyn Nets NBA basketball game in the wake of the explosions at the Boston Marathon. (AP ... more

Photo: Kathy Willens

A police officer patrols the area in front of the Barclays Center... Photo-4477709.60532 - Times Union